select
    o_year,
    sum(case
            when nation = 'IRAN' then volume
            else 0
        end) / sum(volume) as mkt_share
from
    (
        select
            extract(year from o_orderdate) as o_year,
            l_extendedprice * (1 - l_discount) as volume,
            n2.n_name as nation
        from
            part,
            supplier,
            lineitem,
            orders,
            customer,
            nation n1,
            nation n2,
            region
        where
                p_partkey = l_partkey
          and s_suppkey = l_suppkey
          and l_orderkey = o_orderkey
          and o_custkey = c_custkey
          and c_nationkey = n1.n_nationkey
          and n1.n_regionkey = r_regionkey
          and r_name = 'MIDDLE EAST'
          and s_nationkey = n2.n_nationkey
          and o_orderdate between date '1995-01-01' and date '1996-12-31'
          and p_type = 'ECONOMY ANODIZED STEEL'
    ) as all_nations
group by
    o_year
order by
    o_year ;
